Amy Kotsenas
We chose this research topic because we saw several patients with what we called at that time anti-voltage-gated potassium channel complex antibody (VGKC Ab)–related epilepsy.1 We had observed anecdotally that there were similar findings in these patients to other causes of limbic encephalitis, as well as to findings in patients with Creutzfeldt-Jakob disease.2 We now know that in most patients with anti-VGKC complex seizures have antibodies to the leucine-rich glioma-inactivated protein 1 (LGI1) subunit, and in more recent literature it is more commonly referred to by this latter name.
When we analyzed our data, we had 2 unexpected findings: the frequency of bilateral mesial temporal involvement and the association with subsequent mesial temporal sclerosis (MTS). Hippocampal atrophy and T2 hyperintensity are the hallmarks of MTS, but do not point to a specific cause. Prior to our study, investigation for VGKC or LGI1 autoimmunity had not been reported as a suspected cause for idiopathic MTS.
The findings in our paper influence our practice in a few ways. First, when we image patients with suspected autoimmune-related seizures, we always include imaging with diffusion-weighted and contrast-enhanced sequences because this may indicate general prognosis for the development of MTS. The identification of autoimmune causes of epilepsy requires specialized testing with radioimmunoassays, which in many institutions are sent to outside laboratories. For our neurology partners, if we identify the constellation of findings described in the paper, specifically enlarged and T2-hyperintense hippocampus and/or amygdala, they will do these specific tests for autoimmune causes of epilepsy. This early diagnosis seems to be critical for proper treatment with immune-modulating therapy.